MacPhearson-style strut assemblies are well known in the automotive industry. Such assemblies typically comprise a strut which extends upward from the steering knuckle of the wheel and terminates in a top mount which is attached to the chaise of the vehicle. The strut has a rod with a hydraulic cylinder and a spring for absorbing movement of the wheel. The joint between the top mount and the strut contains a strut bearing. A metal spring seat is attached below the bearing and around the rod to terminate and support one end of the spring. A jounce bumper to prevent coil-on-coil compression of spring is mounted also below the bearing and around the rod at the top mount. The strut bearing typically comprises roller bodies or, a synthetic resin sliding bearing.
A typical MacPherson strut assembly is illustrated in FIG. 1. Rod 10 terminates at top mount 11. Between rod 10 and top mount 11 is strut bearing 12 with roller bodies. Spring 13 is housed in spring seat 14 which is conventionally a metal frame. Between spring 13 and spring seat 14, is rubber isolator 15, dust boot 16 extends downward from rubber isolator 15 and jounce bumper 17 is mounted on rod 10 in jounce bumper support cup 18.
There is a need to reduce the overall height of the strut bearing. One way to reduce the height of strut bearing 12, is to use a strut bearing with synthetic resin sliding bearing, see, for example, U.S. Pat. Nos. 4,969,752, 5,476,326, and 6,918,701. One of the drawbacks of these synthetic resins sliding bearing is that, a metal spring seat is needed between the bearing and the spring.